单井涌水量问题的试验和数值模拟研究
发布时间：2018-10-09 17:47
【摘要】：在水文地质调查中,单井涌水量通常用作划分富水性等级的指标,以反映含水层产出地下水的能力。通常用规定口径、规定降深的出水量来表征单井涌水量。单井涌水量受到抽水井本身特性、含水层结构、地下水补给条件以及抽水试验操作方式等因素的影响。一般用三个落程稳定井流抽水试验获得单井涌水量。单位涌水量是指单位降深对应的单井涌水量。针对截取侧向径流的抽水井,兰太权提出一个解释单位涌水量的公式,认为“单位涌水量就是导水系数”(q=T),并以砂箱试验的结果作为证据。然而,这个等式的推导过程缺少严谨的水动力学基础。砂箱试验的边界条件等价于含有1个或2个定水头边界的矩形承压含水层,从理论上表明单位涌水量与导水系数成正比,而比例系数(q/T)取决于含水层的形状(D/L)和抽水井的半径(rw)。在特定条件下,含水层和抽水井的尺寸可以造成单位涌水量与导水系数相等的情况,兰太权发表于文献中的2组砂箱试验恰好符合这种条件,但并不能证明q=T具有普适性。新的砂箱试验避免了几何尺寸的这种特殊组合,得到了显著偏离q=T的结果。通过PMWIN软件对单位涌水量问题进行数值模拟研究,结果表明单位涌水量与导水系数的比值q/T取决于含水层的尺寸(D/L)、抽水井的半径(rw)、非完整井穿透含水层的深度(l/M)和抽水井的位置(x/L,y/L)等因素,但是跟水力梯度没有关系。将这些影响因素特殊组合在一起可能出现单位涌水量等于导水系数的情况,但修改其中一个影响因素就会得到偏离q=T的结果。评估地下水可开采量有简单评估法和模拟评估法两种策略:简单评估法直接套用单位涌水量与最大允许降深的乘积代表地下水可开采量;模拟评估法是通过数值模拟来预测最大允许降深约束下的抽水方案。本文以秦皇岛石门寨水源地为例进行了对比研究。为了防止岩溶塌陷,取抽水井地下水位不低于灰岩顶部作为约束条件,简单评估法得到的地下水可开采量为101341 m3/d,模拟评估法得到的可开采量为31300 m3/d,两者相差甚大。所以,简单利用单井涌水量评估可开采量这种传统策略并不可靠。模拟评估法得到抽水孔单位涌水量与导水系数的比值q/T为0.20~0.71,也显著偏离q=T的条件。
[Abstract]:In hydrogeological survey, single well water discharge is usually used as an index to classify the level of rich water to reflect the ability of aquifer to produce groundwater. A single well water inflow is usually characterized by a specified caliber and a reduced depth of water. The water inflow of single well is affected by the characteristics of pumping well, aquifer structure, groundwater recharge condition and pumping test operation. The water inflow of single well is usually obtained by pumping test of three stable wells. Unit water inflow is a single well water inflow corresponding to unit depth reduction. In view of the pumping wells intercepting lateral runoff, Lan Taiquan puts forward a formula to explain the unit water inflow, which holds that "unit water inflow is the coefficient of water conductivity" (QT), and the results of sand box test are taken as evidence. However, the derivation of this equation lacks a rigorous hydrodynamic basis. The boundary condition of sand box test is equivalent to the rectangular confined aquifer with one or two fixed head boundaries. Theoretically, it is shown that the unit water inflow is proportional to the conductivity coefficient, while the proportional coefficient (Q / T) depends on the shape of the aquifer (D / L) and the radius of the pumping well (rw). Under certain conditions, the size of aquifer and pumping well can make the unit water inflow equal to the coefficient of water conductivity. The two sets of sand box tests published by Lan Taiquan in the literature just meet this condition, but it can not be proved that QT is universal. The new sand box test avoids this special combination of geometric dimensions and obtains a significant deviation from QT. The numerical simulation of unit water inflow is carried out by PMWIN software. The results show that the ratio Q / T of unit inflow to conductivity depends on the size of aquifer (D / L), the depth (l / M) of (rw), nonholonomic well penetrating aquifer and the location of pumping well (x / L y / L), but it has no relation with hydraulic gradient. When these factors are combined together, it is possible that the unit water inflow is equal to the coefficient of water conductivity, but if one of the factors is modified, the result of deviation from QT can be obtained. There are two strategies for evaluating groundwater recoverable quantity: simple evaluation method and simulation evaluation method: simple evaluation method directly applies the product of unit discharge and maximum allowable depth to represent groundwater exploitable amount; The simulation evaluation method is used to predict the pumping scheme with maximum allowable depth reduction constraint by numerical simulation. This paper takes the Shimenzhai water source area of Qinhuangdao as an example to make a comparative study. In order to prevent karst collapse, the groundwater level of pumping well is not lower than the top of limestone as the constraint condition. The recoverable amount of groundwater obtained by simple evaluation method is 101341 m3 / d, and that obtained by simulation evaluation method is 31300 m3 / d, which is quite different between the two methods. Therefore, it is not reliable to simply use the single well water inflow to estimate the recoverable capacity. The ratio Q / T of unit inflow and conductivity of pumping hole is 0.200.71, which deviates significantly from the condition of QT.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P641.7
本文编号：2260208
[Abstract]:In hydrogeological survey, single well water discharge is usually used as an index to classify the level of rich water to reflect the ability of aquifer to produce groundwater. A single well water inflow is usually characterized by a specified caliber and a reduced depth of water. The water inflow of single well is affected by the characteristics of pumping well, aquifer structure, groundwater recharge condition and pumping test operation. The water inflow of single well is usually obtained by pumping test of three stable wells. Unit water inflow is a single well water inflow corresponding to unit depth reduction. In view of the pumping wells intercepting lateral runoff, Lan Taiquan puts forward a formula to explain the unit water inflow, which holds that "unit water inflow is the coefficient of water conductivity" (QT), and the results of sand box test are taken as evidence. However, the derivation of this equation lacks a rigorous hydrodynamic basis. The boundary condition of sand box test is equivalent to the rectangular confined aquifer with one or two fixed head boundaries. Theoretically, it is shown that the unit water inflow is proportional to the conductivity coefficient, while the proportional coefficient (Q / T) depends on the shape of the aquifer (D / L) and the radius of the pumping well (rw). Under certain conditions, the size of aquifer and pumping well can make the unit water inflow equal to the coefficient of water conductivity. The two sets of sand box tests published by Lan Taiquan in the literature just meet this condition, but it can not be proved that QT is universal. The new sand box test avoids this special combination of geometric dimensions and obtains a significant deviation from QT. The numerical simulation of unit water inflow is carried out by PMWIN software. The results show that the ratio Q / T of unit inflow to conductivity depends on the size of aquifer (D / L), the depth (l / M) of (rw), nonholonomic well penetrating aquifer and the location of pumping well (x / L y / L), but it has no relation with hydraulic gradient. When these factors are combined together, it is possible that the unit water inflow is equal to the coefficient of water conductivity, but if one of the factors is modified, the result of deviation from QT can be obtained. There are two strategies for evaluating groundwater recoverable quantity: simple evaluation method and simulation evaluation method: simple evaluation method directly applies the product of unit discharge and maximum allowable depth to represent groundwater exploitable amount; The simulation evaluation method is used to predict the pumping scheme with maximum allowable depth reduction constraint by numerical simulation. This paper takes the Shimenzhai water source area of Qinhuangdao as an example to make a comparative study. In order to prevent karst collapse, the groundwater level of pumping well is not lower than the top of limestone as the constraint condition. The recoverable amount of groundwater obtained by simple evaluation method is 101341 m3 / d, and that obtained by simulation evaluation method is 31300 m3 / d, which is quite different between the two methods. Therefore, it is not reliable to simply use the single well water inflow to estimate the recoverable capacity. The ratio Q / T of unit inflow and conductivity of pumping hole is 0.200.71, which deviates significantly from the condition of QT.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P641.7
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